Very compact wide-angle zoom lens system

Claim 2

A compact wide-angle zoom lens system comprising a first lens group comprising a negative meniscus lens element having a concave surface of the object side and a lens component having negative refractive power, a second lens group comprising a positive cemented doublet lens component and a negative meniscus lens element having a convex surface on the object side and a third lens group comprising at least a positive meniscus lens element having a convex surface on the object side and a cemented doublet lens component, and said lens system being so designed as to change its focal length by displacing said first, second and third lens groups respectively and, in addition, to meet the following conditions: 1.5f<|f.sub.1 |<2f, f.sub.1 <0 (1) 12f<f.sub.2 <15f (2) 0.55f<D.sub.2 <f (3) wherein the reference symbols f represents the focal length of the entire lens system as a whole at its wide position, the reference symbols f 1 and f 2 designate the focal lengths of the first and second lens group respectively and the reference symbol D 2 denotes the total length of the second lens group.

Claim 3

A compact wide-angle zoom lens system according to claim 1 additionally satisfying the following conditions: 0.25f<d.sub.13 +d.sub.14 <0.55f (4) |f'|>5f (5) wherein the reference symbol d 13 +d 14 represents the thickness of the cemented components of the third lens group and the reference symbol f' designates the focal length of the cemented component of the third lens group.

Claim 4

A compact wide-angle zoom lens system according to claim 1 wherein the first lens group consists of a negative meniscus lens element and a negative cemented doublet lens component.

Claim 5

A compact wide-angle zoom lens system according to claim 3 wherein the third lens group consists of a positive meniscus lens element having a convex surface on the object side, a cemented doublet lens component, a negative lens element and a positive lens element, and said lens system having the following numerical data: ______________________________________ f = 1.0 ˜ 1.589 r.sub.1 = 5.2540 d.sub.1 = 0.0815 n.sub.1 = 1.72342 ν.sub.1 = 38.0 r.sub.2 = 1.1981 d.sub.2 = 0.3014 r.sub.3 = -64.0574 d.sub.3 = 0.1935 n.sub.2 = 1.80518 ν.sub.2 = 25.4 r.sub.4 = -1.7706 d.sub.4 = 0.0611 n.sub.3 = 1.51118 ν.sub.3 = 51.0 r.sub.5 = 2.1700 d.sub.5 = 1.2580 ˜ 0.2649 r.sub.6 = 4.3124 d.sub.6 = 0.0815 n.sub.4 = 1.72 ν.sub.4 = 42.1 r.sub.7 = 1.2007 d.sub.7 = 0.4016 n.sub.5 = 1.6485 ν.sub.5 = 45.8 r.sub.8 = -1.4631 d.sub.8 = 0.0766 r.sub.9 = 1.1928 d.sub.9 = 0.0652 n.sub.6 = 1.72342 ν.sub.6 = 38.0 r.sub.10 = 0.6313 d.sub.10 = 0.0288 ˜ 0.0912 r.sub.11 = 0.6403 d.sub.11 = 0.0978 n.sub.7 = 1.804 ν.sub.7 = 46.6 r.sub.12 = 3.7617 d.sub.12 = 0.0570 r.sub.13 = -0.8881 d.sub.13 = 0.0468 n.sub.8 = 1.744 ν.sub.8 = 44.7 r.sub.14 = 0.5475 d.sub.14 = 0.4244 n.sub.9 = 1.67003 ν.sub.9 = 47.3 r.sub.15 = -0.8106 d.sub.15 = 0.0815 r.sub.16 = 3.7634 d.sub.16 = 0.0615 n.sub.10 = 1.78472 ν.sub.10 = 25.7 r.sub.17 = 0.8420 d.sub.17 = 0.0619 r.sub.18 = 3.9741 d.sub.18 = 0.0823 n.sub.11 = 1.58921 ν.sub.11 = 41.1 r.sub.19 = -1.5948 f.sub.1 = -1.7813 f.sub.2 = 11.8158 f.sub.3 = 1.3883 ______________________________________ wherein the reference symbols r 1 through r 19 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 18 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 11 denote refractive indices of the respective lens elements, the reference symbols ν 1 through ν 11 represent Abbe's numbers of the respective lens elements, the reference symbols f 1 through f 3 designate focal lengths of the first, second and third lens groups respectively and the reference symbol f denotes focal length of the lens system as a whole which is expressed taking the focal length at the wide position as 1.

Claim 6

A compact wide-angle zoom lens system according to claim 1 wherein the first lens group consists of a negative meniscus lens element having a convex surface on the object side, a positive lens element and a negative lens element.

Claim 7

A compact wide-angle zoom lens system according to claim 5 wherein the third lens group consists of a positive meniscus lens element having a convex surface on the object side, a cemented doublet lens component, a negative lens element and a positive lens element, and said lens system having the following numerical data: ______________________________________ f = 1.0 ˜ 1.587 r.sub.1 = 5.6713 d.sub.1 = 0.0814 n.sub.1 = 1.72 ν.sub.1 = 42.1 r.sub.2 = 1.1523 d.sub.2 = 0.3255 r.sub.3 = -24.6163 d.sub.3 = 0.1546 n.sub.2 = 1.80518 ν.sub.2 =25.4 r.sub.4 = -2.0972 d'.sub.3 = 0.0081 r'.sub.4 = -2.2618 d.sub.4 = 0.0610 n.sub.3 = 1.50137 ν.sub.3 = 56.4 r.sub.5 = 2.7085 d.sub.5 = 1.3174 ˜ 0.3328 r.sub.6 = 3.2343 d.sub.6 = 0.0814 n.sub.4 = 1.72 ν.sub.4 = 42.1 r.sub.7 = 0.7385 d.sub.7 = 0.3836 n.sub.5 = 1.6485 ν.sub.5 = 45.8 r.sub.8 = -1.4136 d.sub.8 = 0.0765 r.sub.9 = 1.3889 d.sub.9 = 0.0651 n.sub.6 = 1.72342 ν.sub.6 = 38.0 r.sub.10 = 0.6610 d.sub.10 = 0.237 ˜ 0.0786 r.sub.11 = 0.6548 d.sub.11 = 0.1111 n.sub.7 = 1.804 ν.sub.7 = 46.6 r.sub.12 = 7.0504 d.sub.12 = 0.0598 r.sub.13 = -0.9411 d.sub.13 = 0.0468 n.sub.8 = 1.744 ν.sub.8 = 44.7 r.sub.14 = 0.8609 d.sub.14 = 0.3999 n.sub.9 = 1.66998 ν.sub.9 = 39.3 r.sub.15 = -0.9236 d.sub.15 = 0.0500 r.sub.16 = 6.3609 d.sub.16 = 0.0614 n.sub. 10 = 1.78472 ν.sub.10 = 25.7 r.sub.17 = 0.8373 d.sub.17 = 0.0618 r.sub.18 = -48.3564 d.sub.18 = 0.0822 n.sub.11 = 1.58913 ν.sub.11 = 61.1 r.sub.19 = -1.0554 f.sub.1 = -1.7791 f.sub.2 = 11.8013 f.sub.3 = 1.3873 ______________________________________ wherein the reference symbols r 1 through r 19 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 18 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 11 denote refractive indices of the respective lens elements, the reference symbols ν 1 through ν 11 represent Abbe's numbers of the respective lens elements, the reference symbols f 1 through f 3 designate focal lengths of the first, second and third lens groups respectively and the reference symbol f denotes focal length of the lens system as a whole which is expressed taking the focal length at the wide position as 1.

Claim 8

A compact wide-angle zoom lens system according to claim 3 wherein the third lens group consists of a positive meniscus lens element having a convex surface on the object side, a cemented doublet lens component, a negative lens element and a positive lens element, and said lens system having the following numerical data: ______________________________________ f = 1.0 ˜ 1.458 r.sub.1 = 2.4225 d.sub.1 = 0.0816 n.sub.1 = 1.713 ν.sub.1 = 53.9 r.sub.2 = 1.1551 d.sub.2 = 0.4082 r.sub.3 = -33.2515 d.sub.3 = 0.2041 n.sub.2 = 1.80518 ν.sub.2 = 25.4 r.sub.4 = -2.6202 d.sub.4 = 0.0612 n.sub.3 = 1.50137 ν.sub.3 = 56.4 r.sub.5 = 1.4239 d.sub.5 = 1.1889 ˜ 0.4151 r.sub.6 = 2.6396 d.sub.6 = 0.4412 n.sub.4 = 1.68893 ν.sub.4 = 31.1 r.sub.7 = 0.9257 d.sub.7 = 0.3633 n.sub.5 = 1.6516 ν.sub.5 = 58.7 r.sub.8 = -1.8282 d.sub.8 = 0.0041 r.sub.9 = 1.4003 d.sub.9 = 0.0657 n.sub.6 = 1.72342 ν.sub.6 = 38.0 r.sub.10 = 0.6641 d.sub.10 = 0.0378 ˜ 0.0901 r.sub.11 = 0.6873 d.sub.11 = 0.1102 n.sub.7 = 1.7859 ν.sub.7 = 44.1 r.sub.12 = 6.3436 d.sub.12 = 0.1224 r.sub.13 = -0.8140 d.sub.13 = 0.0506 n.sub.8 = 1.72 ν.sub.8 =43.7 r.sub.14 = 0.7542 d.sub.14 = 0.2600 n.sub.9 = 1.66998 ν.sub.9 = 39.3 r.sub.15 = -0.8544 d.sub.15 = 0.0531 r.sub.16 = 2.1073 d.sub.16 = 0.0612 n.sub.10 = 1.78472 ν.sub.10 =25.7 r.sub.17 = 0.8296 d.sub. 17 = 0.0694 r.sub.18 = -6.8119 d.sub.18 = 0.0816 n.sub.11 = 1.58913 ν.sub.11 = 61.1 r.sub.19 = -1.0722 f.sub.1 = -1.6220 f.sub.2 = 13.3478 f.sub.3 = 1.3030 ______________________________________ wherein the reference symbols r 1 through r 19 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 18 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 11 denote refractive indices of the respective lens elements, the reference symbols ν 1 through ν 11 represent Abbe's numbers of the respective lens elements, the reference symbols f 1 through f 3 designate focal lengths of the first, second and third lens groups respectively and the reference symbol f denotes focal length of the lens system as a whole which is expressed taking the focal length at the wide position as 1.

Claim 9

A compact wide-angle zoom lens system according to claim 3 wherein the third lens group consists of a positive meniscus lens element having a convex surface on the object side, a cemented doublet lens component, a negative lens element and a positive lens element, and said lens system having the following numerical data: ______________________________________ f = 1.0 ˜ 1.456 r.sub.1 = 2.7119 d.sub.1 = 0.0817 n.sub.1 = 1.713 ν.sub.1 = 53.9 r.sub.2 = 1.2463 d.sub.2 = 0.3876 r.sub.3 = -37.0068 d.sub.3 = 0.2185 n.sub.2 = 1.80518 ν.sub.2 = 25.4 r.sub.4 = -2.6686 d.sub.4 = 0.0613 n.sub.3 = 1.50137 ν.sub.3 = 56.4 r.sub.5 = 1.3744 d.sub.5 = 1.1828 ˜ 0.4084 r.sub.6 = 3.0705 d.sub.6 = 0.4624 n.sub.4 = 1.68893 ν.sub.4 = 31.1 r.sub.7 = 0.9025 d.sub.7 = 0.3640 n.sub.5 = 1.6516 ν.sub.5 = 58.7 r.sub.8 = -1.6293 d.sub.8 = 0.0041 r.sub.9 = 1.3059 d.sub.9 = 0.0874 n.sub.6 = 1.72342 ν.sub.6 = 38.0 r.sub.10 = 0.6312 d.sub.10 = 0.0322 ˜ 0.0846 r.sub.11 = 0.6471 d.sub.11 = 0.1144 n.sub.7 = 1.7859 ν.sub.7 = 44.1 r.sub.12 = 3.6198 d.sub.12 = 0.0609 r.sub.13 = -1.0349 d.sub.13 = 0.0408 n.sub.8 = 1.697 ν.sub.8 = 48.5 r.sub.14 = 1.8342 d.sub.14 = 0.2749 n.sub.9 = 1.64769 ν.sub.9 = 33.8 r.sub.15 = -1.2644 d.sub.15 = 0.1156 r.sub.16 = 4.3007 d.sub.16 = 0.0613 n.sub.10 = 1.78472 ν.sub.10 = 25.7 r.sub.17 = 0.9236 d.sub.17 = 0.0613 r.sub.18 = -10.0803 d.sub.18 = 0.1021 n.sub.11 = 1.618 ν.sub.11 = 63.38 r.sub.19 = -0.8906 f.sub.1 = -1.6232 f.sub.2 = 13.3582 f.sub.3 = 1.3062 ______________________________________ wherein the reference symbols r 1 through r 19 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 18 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 11 denote refractive indices of the respective lens elements, the reference symbols ν 1 through ν 11 represent Abbe's numbers of the respective lens elements, the reference symbols f 1 through f 3 designate focal lengths of the first, second and third lens groups respectively and the reference symbol f denotes focal length of the lens system as a whole which is expressed taking the focal length at the wide position as 1.